Endodontic instruments and root canal treatment methods

ABSTRACT

Instruments and associated methods for performing endodontic treatment and that demand less time and fatigue onto the dentists and patients, while presenting the following accomplishments: debride the root canals in three dimensions and performing the optimal treatment; shape the root canals to facilitate the irrigation; these instruments are resistant to breakage and pressure while operating at high speed and torque; the instruments are capable of bypassing most obstacles, broken files, hypercalcification, curved roots canals, shoulders, and residual resistant pastes; and they present an alternative to arduous and expensive surgeries like endodontic or implant surgeries. As a result, they prevent fractures and procedural errors in making false canals or perforations of the root canals.

FIELD OF THE INVENTION

The present invention relates to instruments for endodontic use, andmore particularly to apparatuses and associated methods for performingroot canal treatment.

BACKGROUND OF THE INVENTION

In endodontics it is necessary to thoroughly debride a root canal (orpulp chamber) of a tooth, in order to reduce the chances of bacterialgrowth in the root canal, and to improve the healing potential of theremaining healthy tissue. As used herein, debridement includes forexample, the removal of dead, damaged, or infected tissue of the dentalpulp, as well as hypercalcification, residual resistant paste, variousconstrictions, broken instruments, and fragments or foreign materiallodged in the root canal.

This debridement would ideally terminate at the apical foramen. Theapical foramen is the opening at the apex of the root of the tooth,through which the nerve and blood vessels that supply the dental pulppass. The dental pulp resides in the root canal and is comprised ofliving circulatory, connective, and nerve tissues.

As part of the endodontic therapy, and following the debridement of theroot canal, the endodontic clinician shapes the root canal prior toinserting a filler material in place of the original dental pulp.

To this end, hand (i.e., manual) files and rotary files (i.e.,electrically operated) commonly called spiral instruments are used forthe treatment of root canals. Typically, these spiral instruments have agenerally triangular, square, or rectangular cross section, and compriseedges (or corners) that attack the dental wall and strike the dentinewall at an acute angle. Consequently, these conventional files have atendency to wear out prematurely and to break.

In addition, these conventional files may bind when resisted byobstacles and eventually break inside the root canal, as they do nothave a sufficient thickness to resist torsion fatigue induced thereon.Moreover, such files do not generally perform a complete rubbing of thedental wall in order to achieve a hermetic obturation of the root canal,thus yielding to a risk of infection.

In addition, the tip of these spiral instruments is usually anon-cutting tip based on the assumption that a cutting tip willfacilitate the formation of false canals.

Conventionally, withdrawing segments of fractured instruments that causeroot obstructions, was done by means of ultrasonic files. An exemplarytechnique requires the use of conventional manual files from No. 8 to 15having a taper of 2%, in order to open a cutting around the lodgedsegment of the fractured instrument. However, this withdrawal techniqueinvolves the risk of introducing additional breakage of the newly usedinstrument, as well as opening false canals. As a result, thisconventional technique has not generally yielded optimal results.

Furthermore, in order to overcome obstructions resulting fromhypercalcification, certain conventional treatment methods propose theenlargement of the root canal using files from No. 8 to 15 having a 2%taper, or C+ files followed by the use of rotary files (electricallyoperated) from No. 10 to 25 with a 2%, 4%, or 6% taper. However, thismethod also does not provide optimal results and introduces the risk ofbreakage of the newly used file, as well as opening false canals.

The weakness of the conventional endodontic files in fracture or inprocedural errors, is due to their cyclic fatigue and torsional stress,and the difficulties of removing the broken files, as explained in thefollowing publications:

-   Bahcall J K, et al., “The causes, prevention, and clinical    management of broken endodontic rotary files,” Dent Today. 2005    November; 24(11):74, 76, 78-80; quiz 80, Department of Surgical    Sciences, Marquette University School of Dentistry, USA, the    abstract of which is available online at    http://www.ncbi.nlm.nih.gov/pubmed/16358801.-   Peters O. A., “Rotary Instrumentation: An endodontic perspective,”    American Association of Endodontists, Winter 2008, which is    available online at    https://www.aae.org/uploadedfiles/publications_and_research/endodontics_colleagues_for_excellence_newsletter/winter08ecfe.pdf.    This publication makes it clear that not all root canals lend    themselves to rotary preparation, due to varying degrees of the    clinicians' skills and case complexity, and to the fact that rotary    files may fracture rather unexpectedly or create procedural errors.

The following references clarify that the fracture of an endodontic filemay cause the endodontic treatment to have a lower success rate, andthat fragments of files may be removed using a retrieval system;however, this procedure can be technically demanding, and severalfragments may be left in-situ:

-   Metzger, Z. et al., “The Self-Adjusting File (SAF). Part 1:    Respecting the Root Canal Anatomy—A New Concept of Endodontic Files    and Its Implementation,” Journal of Endodontics 36 (4): 679-90    (2010).-   De-Deus, G. et al., “The Self-Adjusting File Optimizes Debridement    Quality in Oval-shaped Root Canals,” Journal of Endodontics 37 (5):    701-5 (2011).-   Siqueira Jr., J. F., et al. “Ability of Chemomechanical Preparation    with Either Rotary Instruments or Self-Adjusting File to Disinfect    Oval-shaped Root Canals,” Journal of Endodontics 36 (11): 1860-5    (2010).

Although cylindro conical instruments have been used by dentists only inroot canal filing material (spreaders) with a smooth surface, they havenot been used to probe, shape, debride, catheterize, penetrate or bypassobstacles in root canal treatments. Reference is made to Carrotte, P.,“Endodontics: Part 5 Basic instruments and materials for root canaltreatment,” British Dental Journal 197, 455-464 (2004), Publishedonline: 23 Oct. 2004, athttp://www.nature.com/bdj/journal/v197/n8/full/4811738a.html Root canalfilling instruments.

In addition to the risks involved with the use of conventional treatmentmethods, there is a potential for damaging the apex or causing a shearin the coronal part or in the apical part of the root canal.

Yet another disadvantage of the conventional treatment methods is thatthe instruments generally cannot penetrate difficulthypercalcifications, blockages, and narrow canals, nor can they probethe ledges or pierce the most resistant residual paste in the rootcanal.

In addition, they cannot bypass lodged segments of fractured instrumentsin the root canals, nor can they remove dental plugs. Moreover, theycannot penetrate blockages resulting from root canal treatment, nor canthey penetrate the obliterated coronary infundibula due to the highfracture risk.

Still another disadvantage of the conventional treatment methods is thatthe instruments generally may not be totally suitable for use underelevated torque or high speed, due to the high fracture risk. Inaddition, the spiral instruments generally exert force on the dentalwall and are therefore subjected to a reactive force. In fact, rubbingthe dental wall does not facilitate penetration in the desired directionof the dental apex.

Wherefore, there still remains an unsatisfied need for new endodonticinstruments and associated methods of use for performing better rootcanal treatment. These instruments should penetrate or bypass most, ifnot all blockages in the root canals, while achieving optimal root canaltreatment with optimal root canal shape, in order to maximize irrigationand hermetic obturation of the root canals.

SUMMARY OF THE INVENTION

The present invention satisfies this need, and presents severalpreferred designs for endodontic instruments and associated methods ofuse for performing root canal treatment. These instruments penetrate orbypass most, if not all blockages in the root canal, while achievingoptimal root canal treatment with optimal root canal shape, in order tomaximize irrigation and hermetic obturation of the root canal.

In addition, the treatment of a root canal with the instruments andmethods of the present invention, while avoiding damage to either theroot canal or the apex, is ensured a very high rate of success.

Although the teeth and grooves of the endodontic instruments of thepresent invention may become worn with use, they will not easily breakbecause they do not attack the radical dentine at weak pointed angles.In addition, the use of sandblasting to form the endodontic instrumenthelps to avoid corrosion of instrument resulting from stocking, storage,or usage.

The various instruments of the invention surpass the conventionalstainless steel hand files and the NiTi rotary instruments, and presentnumerous advantages among which are the following:

The instruments are very flexible so that they may follow difficultcurved root canals without damaging the apex, making a false canal, orcausing a shear in the coronal part and the apex of the root canal.

They penetrate the difficult hypercalcifications, obstructions andnarrow canals.

They probe the ledges of the root canal.

They pierce residual, resistant pastes.

They bypass fractured files, lentulos, posts, and fractured silvercones.

They do not create false canals, shears and dental plugs.

They allow the removal of pre-existing dental plugs.

They penetrate blockages caused by an inadequate use of otherinstruments.

They penetrate the obliterated coronary infundibula with low risk offracture or of damaging the apex.

Furthermore, these instruments successfully perform and facilitate thecomplete endodontic procedure:

They penetrate root canals that other endodontic instruments fail topenetrate.

They resist increased torque and high speeds (ranging from approximately1.5 N to 5 N and from approximately 300-600 rpm) due to their highresistance.

Their success in treating and retreating root canals helps to avoidexpensive and painful endodontic surgeries and eventually implants incase of failure of endodontic treatments.

To this end, each instrument of the present invention comprises a handlethat secures an elongated tapered shank. The shanks of the instrumentsinclude cylindro-conical files having a circular cross section, whichpenetrate the root canals using most, if not the entirety of theirperipheral surfaces, thus providing a better ability to resist torsionfatigue, to preserve the initial circular dental canal anatomy, and toattain a hermetical obturation of the root canals. The shanks can assumea variety of designs based on a combination of characteristics,including but not limited to: a roughed surface, a cutting surface, asmooth area, a conical cutting tip, a non-cutting tip, a beveled tip,and a non-beveled tip.

Based upon the various designs of their shanks, the endodonticinstruments may generally be categorized, as follows:

-   -   1^(st) Category: Instruments for catheterization and for passing        through root obstacles.    -   2^(nd) Category: Instruments for fine and curved roots.    -   3^(rd) Category: Instruments that may be used for enlarging and        shaping root canals.

The instruments in the 1^(st) Class of the 1^(st) Category can be eitherhand operated or electrically rotating. Each of these instrumentsincludes a lateral surface that contains a number of superficialhorizontally, vertically, or transversally striated grooves that defineslightly cutting edges, and that are either separated by smooth areas orsandblasted areas. The instruments in this class include a generallycircular cross-section, and a conical tip that may be cutting ornon-cutting, beveled or non-beveled. These instruments include handoperated files for root canal treatment that are preferably made fromstainless steel (with nos. ranging from 10 to 25) or NiTi (with nos.ranging from 20 to 25) and electrically rotating NiTi files (with nos.ranging from 10-to 25), all with a taper of approximately 0, 1, 2, 3, or4% and a length ranging from approximately 12 mm-32 mm.

The instruments in the 2^(nd) Class of the 1^(st) Category are handoperated instruments having a series of horizontally, vertically, ortransversally striated deep grooves with cutting edges, that areseparated by restricted smooth or sandblasted areas or even instrumentsthat are completely sandblasted. The instruments in this class include agenerally circular cross section, and a conical tip that may be cuttingor non-cutting. The shanks of these instruments range from No. 6 to 20.The shanks may be made from stainless steel, and range from No. 6 to 20.The shanks may alternatively be made from NiTi, and range from No. 20 to40. The shafts of all these instruments have a taper of approximately0%, 1%, 2%, and 4%, and a length that ranges from approximately 12 mm to32 mm.

The instruments of the 2^(nd) Category preferably include electricallyoperated rotating NiTi instruments, each having a tapered shank with aseries of transversal, deep, striated grooves with cutting edges. Inother embodiments can alternatively, the instruments include a series ofhorizontally or vertically striated, deep grooves with cutting edges,that are separated by either smooth or roughened (i.e., sandblasted)restricted areas. These instruments include electrically rotating filesfor root canal treatment with nos. 10 to 20, and having an approximate2% taper and a length ranging from approximately 21 mm to 32 mm.

The instruments of the 3^(rd) Category preferably include electricallyoperated rotating instruments, each having a shank with a generallycircular cross section and a conical cutting or non-cutting tip, with aseries of saw teeth that are separated by restricted smooth areas. Inother embodiments, the shank can include horizontally, vertically, ortransversally striated grooves. These instruments include electricallyrotating files for root canal treatment with nos. ranging from 20 to 40,and having an approximate 4% to 10% taper and a length ranging fromapproximately 21 mm to 32 mm.

The endodontic procedure being administered determines the selection ofthe category, the instruments within each category, and the sequentialuse of the selected instruments.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features of the present invention and the manner ofattaining them will be described in greater detail with reference to thefollowing description, claims, and drawings, wherein reference numeralsare reused, where appropriate, to indicate a correspondence between thereferenced items, and wherein:

FIG. 1 comprises FIGS. 1A and 1B, and represents two schematicillustrations of an exemplary hand operated (or electrically rotating)instrument having a long, tapered shank which includes superficialhorizontally striated grooves with slightly cutting edges that areseparated by smooth areas (FIG. 1A), and which includes deephorizontally striated grooves with cutting edges that are separated byrestricted smooth areas (FIG. 1B), according to preferred embodiments ofthe present invention;

FIG. 2 comprises FIGS. 2A and 2B, and represents two schematicillustrations of an exemplary hand operated (or electrically rotating)instrument having a long, tapered shank which includes superficialvertically striated grooves with slightly cutting edges that areseparated by smooth areas (FIG. 2A), and which includes deep verticallystriated grooves with cutting edges that are separated by restrictedsmooth areas (FIG. 2B), according to preferred embodiments of thepresent invention;

FIG. 3 comprises FIGS. 3A and 3B, and represents two schematicillustrations of an exemplary hand operated (or electrically rotating)instrument having a long, tapered shank which includes continuous,superficial transversally striated grooves with slightly cutting edgesthat are separated by smooth areas (FIG. 3A), and which includes deeptransversally striated grooves with cutting edges that are separated byrestricted smooth areas (FIG. 3B), according to preferred embodiments ofthe present invention;

FIG. 4 is a schematic illustration of an exemplary hand operated (orelectrically rotating) instrument having a long, tapered shank with abeveled tip, and discontinuous, superficial transversally striatedgrooves with slightly cutting edges, separated by smooth areas,according to a preferred embodiment of the present invention;

FIG. 5 is a schematic illustration of an exemplary hand operated (orelectrically rotating) instrument having a long, tapered shank withsuperficial transversally striated grooves with slightly cutting edges,separated by roughened areas (such as by sandblasting), according to apreferred embodiment of the present invention;

FIG. 6 is a schematic illustration of an exemplary hand operatedinstrument having a long, tapered shank with deep transversally striatedgrooves with cutting edges, separated by restricted smooth areas,according to a preferred embodiment of the present invention;

FIG. 7 is a schematic illustration of an exemplary electrically rotatinginstrument having a long, tapered shank with deep transversally striatedgrooves with cutting edges, separated by restricted smooth areas,according to a preferred embodiment of the present invention;

FIG. 8 is a schematic illustration of an exemplary electrically rotating(or hand operated) instrument having a long, tapered shank with a seriesof saw teeth separated by restricted smooth areas, according to apreferred embodiment of the present invention;

FIG. 9 comprises FIGS. 9A and 9B, and represents two schematicillustrations of an exemplary hand operated (FIG. 9B) and electricallyrotating (FIG. 9A) spiral instrument with an upper cylindro-conical parthaving a conical tip, wherein the cylindro-conically shaped area isroughened, for example, by transversally grooved striations with cuttingedges separated by restricted smooth or sandblasted areas, according topreferred embodiments of the present invention;

FIG. 10 comprises FIGS. 10A and 10B, and represents two schematicillustrations of an exemplary hand operated (FIG. 10B) and electricallyrotating (FIG. 10A) instrument having a conical tip and a long,generally tapered shank that defines a series of cylindro-conicallyshaped areas (or sections) separated by spirally shaped sections,wherein the cylindro-conically shaped areas (or sections) are roughenedby, for example, transversally grooved striations with cutting edgesseparated by restricted smooth areas, according to preferred embodimentsof the present invention;

FIG. 11 comprises FIGS. 11A and 11B, and represents two schematicillustrations of an exemplary hand operated (FIG. 11B) and electricallyrotating instrument (FIG. 11A) having a long, generally tapered shankthat defines a series of spirally shaped sections separated bycylindro-conically shaped areas (or sections) that are roughened by, forexample, transversally grooved striations with cutting edges separatedby restricted smooth areas, according to preferred embodiments of thepresent invention;

FIG. 12 comprises FIGS. 12A and 12B, and represents two schematicillustrations of an exemplary hand operated (FIG. 12B) and electricallyrotating (FIG. 12A) instrument having a conical tip and a long,generally tapered sand blasted shank that defines a series ofcylindro-conically shaped areas (or sections) separated by spirallyshaped sections, wherein the cylindro-conically shaped areas (orsections) are roughened by, for example, transversally groovedstriations with cutting edges separated by restricted sand blastedareas, according to preferred embodiments of the present invention;

FIG. 13 comprises FIGS. 13A, 13B, 13C, and 13D, and illustrates across-sectional view of an exemplary tooth, with the cross-hatchingremoved for clarity of illustration, showing the sequential steps ofprogressively treating a root canal without a resistive path,obstruction, or blockage, using the instrument and process of thepresent invention;

FIG. 14 comprises FIGS. 14A, 14B, 14C, 14D, 14E, and 14F, andillustrates a cross-sectional view of an exemplary tooth, with thecross-hatching removed for clarity of illustration, showing thesequential steps of progressively treating a root canal that is blockedby a fragment of a broken instrument, such as a file, by bypassing thelodged fragment using the instrument and process of the presentinvention;

FIG. 15 comprises FIGS. 15A, 15B, and 15C and illustrates across-sectional view of an exemplary tooth, with the cross-hatchingremoved for clarity of illustration, showing the sequential steps ofprogressively treating a root canal that is blocked byhypercalcification, by piercing the hypercalcification using theinstrument and process of the present invention;

FIG. 16 comprises FIGS. 16A, 16B, and 16C and illustrates across-sectional view of an exemplary tooth, with the cross-hatchingremoved for clarity of illustration, showing the sequential steps ofprogressively treating a root canal that is partially blocked by ashoulder, by bypassing the shoulder using the instrument and process ofthe present invention;

FIG. 17 comprises FIGS. 17A, 17B, and 17C and illustrates across-sectional view of an exemplary tooth, with the cross-hatchingremoved for clarity of illustration, showing the sequential steps ofprogressively treating a root canal that is blocked by a residualresistant paste, by piercing and removing the resistant paste using theinstrument and process of the present invention;

FIG. 18 is a flow chart that illustrates the endodontic treatmentprocess that does not exhibit signs of a resistive path, obstruction, orblockage, by selectively using the instruments of FIGS. 1B, 2B, 3B, and6 through 8 according to the present invention;

FIGS. 19A and 19B represent a flow chart that illustrates the endodontictreatment method of bypassing root obstructions resulting from fracturedinstruments, by selectively using the instruments of FIGS. 1A, 1B, 2A,2B, 3A, 3B, and 4 through 8 according to the present invention;

FIGS. 20A and 20B represent a flow chart that illustrates the endodontictreatment method of penetrating root obstructions resulting fromhypercalcification, by selectively using the instruments of FIGS. 1A,1B, 2A, 2B, 3A, 3B, and 5 through 8 according to the present invention;

FIGS. 21A and 21B represent a flow chart that illustrates the endodontictreatment method of bypassing root obstructions resulting from ashoulder obstruction, by selectively using the instruments of FIGS. 1A,1B, 2A, 2B, 3A, 3B, and 5 through 8 according to the present invention;

FIGS. 22A and 22B represent a flow chart that illustrates the endodontictreatment method of penetrating root obstructions resulting from aprevious root canal treatment, by selectively using the instruments ofFIGS. 1A, 1B, 2A, 2B, 3A, 3B, and 4 through 8 according to the presentinvention; and

FIGS. 23A, 23B, 23C, 24A, 24B, 24C, 25A, 25B, 25C, 25D, 26A, 26B, 27A,27B, 27C, 28A, 28B, 28C, 28D, 29A, 29B, 29C, 30A, 30B, 31A, 31B, 32A,32B, 32C, 33A, 33B, 33C, 33D, 34, 35, 36A, 36B, 36C, 37A, 37B, 38A, and38B are X-ray views that illustrate various cases treated by theinstruments and methods of the present invention.

It should be understood that the sizes of the different components inthe figures might not be in exact proportion, and are shown for visualclarity and for the purpose of explanation.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The instruments of the present invention can be used for probing,enlarging, penetrating, and bypassing difficult root canalsobstructions, they may be hand operated or electrically operated, theymay have a continued or a discontinued rotation, and they may havereciprocal rotation, a clockwise rotation, or an anti-clockwiserotation.

As it will be explained later in more specific details, each of theseinstruments comprises a handle that secures an elongated tapered shank.The cross section of the shank is generally circular, so as to eliminatesharp edges (or corners) that might otherwise attack the dental wall andstrike the dentine wall at an acute angle, thus ultimately extending thelife of the instrument.

The shank can assume a variety of designs, based on a combination ofcharacteristics, including but not limited to: a roughed surface, acutting surface, a smooth area, a conical cutting tip, a non-cuttingtip, a beveled tip, and a non-beveled tip.

Based upon the various designs of their shanks, the endodonticinstruments may be categorized as follows:

-   -   1^(st) Category: Instruments for catheterization and for passing        through root obstacles.    -   2^(nd) Category: Instruments for fine and curved roots.    -   3^(rd) Category: Instruments that may be used for enlarging and        shaping root canals.

Each of these categories will now be described in more detail.

1st Category: Instruments for Catheterization and for Passing ThroughRoot Obstacles, Shoulders, Resistant Paste, and Hypercalcifications

This category comprises two classes of instruments:

First (1^(st)) Class: Instruments for Passing Through Root Obstacles,Shoulders, Resistant Paste, and Hypercalcifications

This class includes hand operated and electrically rotating instrumentshaving a number of superficial horizontally, vertically, ortransversally striated grooves (also referred to as “shallow grooves”)that define slightly cutting edges, and that are either separated bysmooth areas or sandblasted areas or even instruments that arecompletely sandblasted. As used herein, the term “shallow” denotes ageneral depth that ranges between approximately 0.06 mm and 0.4 mm. Theinstruments in this class include a generally circular cross-section,and a conical tip that may be cutting or non-cutting, beveled ornon-beveled.

The shanks of the hand operated instruments may be made from stainlesssteel, and range from No. 10 to 25. The shanks of the hand operatedinstruments that are made from NiTi, preferably range from No. 20 to 25.The shafts of the electrically rotating NiTi instruments preferablyrange from No. 10 to 25. The shafts of all these instruments have ataper ranging from approximately 0% to 4%, and a length that ranges fromapproximately 12 mm to 32 mm. (FIGS. 1-5).

The more preferred embodiments of the instruments in this class thatprovide optimal results are the hand operated instruments Nos. 10, 15,and 20, with a shank taper with an approximate 2% taper, and that aremade from stainless steel. Other preferred embodiments include the handoperated instruments No. 20 with an approximate 4% shank taper that ismade from NiTi. Additional preferred embodiments include theelectrically rotating instruments that are made from NiTi, Nos. 10, 15,and 20, with a shank taper of approximately 2%, and Nos. 20 and 25 witha shank taper of approximately 4%.

Sandblasted instruments with superficial grooves with slightly cuttingedges, have provided good penetration results, namely in engraving acutting adjacent to the fractured instrument without encroaching withthe coils of the fractured instrument, and in removing the dentine ofthe root canal. Optimal penetration results have been obtained withinstruments that are sandblasted with aluminum oxide.

Second (2^(nd)) Class: Instruments for Catheterization

This class includes hand operated instruments having a series ofhorizontally, vertically, or transversally striated deep grooves withcutting edges, that are separated by restricted smooth or sandblastedareas or even instruments that are completely sandblasted. As usedherein, the term “deep” denotes a general depth that ranges betweenapproximately between 0.12 mm and 0.8 mm. The instruments in this classinclude a generally circular cross section, and a conical tip that maybe cutting or non-cutting.

The shanks of these instruments range from No. 6 to 20. The shanks maybe made from stainless steel, and range from No. 6 to 20. The shanks mayalternatively be made from NiTi, and range from No. 20 to 40. The shaftsof all these instruments have a taper of approximately 0%, 1%, 2%, and4%, and a length that ranges from approximately 12 mm to 32 mm (FIG. 6).The preferred embodiments of the instruments in this class that provideoptimal results are those made of stainless steel with Nos. 10, 15, and20, with an approximate 2% taper. These preferred embodiments includeinstruments that are made from NiTi, No. 20, with an approximate 4%shank taper.

The instruments of this 1^(st) category will now be described withreference to FIGS. 1 through 6. FIG. 1A is a schematic illustration ofan exemplary hand operated instrument (or file) 100 for use as a firstcategory, first class instrument, according to a preferred embodiment ofthe present invention. The instrument 100 generally includes anelongated, tapered shank 105 with superficial horizontally striatedgrooves 110 with slightly cutting edges that are separated by smoothareas 111.

In one exemplary embodiment, the grooves 110 form horizontal linearstriations that are approximately 1 mm wide. It should be understoodthat the grooves 110 might assume other different patterns. The width ofeach smooth area 111 varies between approximately 2 mm and 3 mm.

The instrument 100 further includes a tip 120 and a handle 125. The tip120 may be cutting or non-cutting, beveled or non beveled, depending onthe desired application. The handle 125 secures one end of the shank105, and enables an endodontist to safely and ergonomically hold theinstrument 100 while performing the treatment. It should be understoodthat the instrument 100 may alternatively be electrically rotating, inwhich case, the handle 125 is replaced with an appropriate handle orinterface that connects the shank 105 to an external rotary source (notshown), as is known or available in the field.

The shank 105 can be made of any suitable material, including but notlimited to stainless steel or NiTi (Nickel Titanium). The shank 105 mayhave a constant or variable taper along its axial length, ranging fromapproximately 0% to 4%, a length ranging from approximately 12 mm to 32mm, and a width ranging from approximately No. 10 to 25.

FIG. 1B illustrates another instrument 150 for use as a first category,second class instrument according to a preferred embodiment of thepresent invention. The instrument 150 may also be used as a second orthird category instrument, as explained herein.

The instrument 150 is generally similar in design and construction tothe instrument 100 of FIG. 1A, and comprises an elongated, tapered shank155 with deep horizontally striated grooves 160 with cutting edges thatare separated by restricted smooth areas 161. In one exemplaryembodiment, the grooves 160 form horizontal linear striations that areapproximately 2 to 3 mm wide. It should be understood that the grooves160 might assume other patterns. The width of each smooth area 161 isapproximately 1 mm.

The instrument 150 further includes a cutting or non-cutting tip 120 anda handle 125, whose design and function are explained earlier inconnection with the instrument 100.

It should be understood that these instruments 100, 150 can be modified,as explained herein, for use as electrically rotating instruments.

FIG. 2 respectively illustrates two exemplary hand operated instruments200 (FIG. 2A) and 250 (FIG. 2B) that are generally similar in design andconstruction to the instruments 100, 150 (respectively) of FIG. 1. Itshould be understood that these instruments 200, 250 can be modified, asexplained herein, for use as electrically rotating instruments.

The instrument 200 can be used as a first category, first classinstrument. It includes an elongated, tapered shank 205 with superficialvertically striated grooves 210 with slightly cutting edges that areseparated by smooth areas 211, according to a preferred embodiment ofthe present invention. In one exemplary embodiment, the grooves 210 formvertical linear striations that are approximately 1 mm in width. Thesmooth areas 211 separate the grooves 210 at a distance of approximately2 to 3 mm.

The instrument 200 further includes a cutting or non-cutting tip 220 anda handle 125, which are respectively similar to the tip 120 and handle125 of the instrument 100 of FIG. 1A.

The instrument 250 of FIG. 2B can be used as a first category, secondclass instrument, according to a preferred embodiment of the presentinvention. It may also be used as a second or third category instrument,as explained herein. The instrument 250 includes an elongated, taperedshank 255 having deep vertically striated grooves 260 with cutting edgesthat are separated by restricted smooth areas 261. In one exemplaryembodiment, the grooves 260 form vertical linear striations that areapproximately 2 to 3 mm in width. The smooth areas 261 separate thegrooves 260 at a distance of approximately 1 mm.

The instrument 250 further includes a cutting or non-cutting tip 220 anda handle 125, which are respectively similar to the tip 120 and handle125 of the instrument 150 of FIG. 1B.

FIG. 3 respectively illustrates two exemplary hand operated instruments300 (FIG. 3A) and 350 (FIG. 3B) that are generally, respectively similarin design and construction to the instruments 100, 150 of FIG. 1 and200, 250 of FIG. 2. It should be understood that these instruments 300,350 can be modified, as explained herein, for use as electricallyrotating instruments.

The instrument 300 can be used as a first category, first classinstrument. It includes an elongated, tapered shank 305 with superficialtransversally striated grooves 310 with slightly cutting edges that areseparated by smooth areas 311, according to a preferred embodiment ofthe present invention. In one exemplary embodiment, the grooves 310 formtransversally linear striations that are approximately 1 mm in width.The smooth areas 311 separate the grooves 310 at a distance ofapproximately 2 mm to 3 mm.

The instrument 300 further includes a cutting or non-cutting tip 320 anda handle 125, which are respectively similar to the tip 120 and handle125 of the instrument 100 of FIG. 1A.

The instrument 350 of FIG. 3B can also be used as a first category,second class hand operated instrument, according to a preferredembodiment of the present invention. It may also be used as a second orthird category instrument, as explained herein. The instrument 350includes an elongated, tapered shank 355 with deep transversallystriated grooves 360 with cutting edges that are separated by restrictedsmooth areas 361. In one exemplary embodiment, the grooves 360 formtransversally linear striations that are approximately 2 to 3 mm inwidth. The smooth areas 361 separate the grooves 360 at a distance ofapproximately 1 mm.

The instrument 350 further includes a cutting or non-cutting tip 320 anda handle 125, which are respectively similar to the tip 120 and handle125 of the instrument 150 of FIG. 1B.

FIG. 4 illustrates an exemplary hand operated instrument 400 that isgenerally similar in design and construction to the instrument 300 ofFIG. 3A. It should be understood that the instrument 400 can bemodified, as explained herein, for use as an electrically rotatinginstrument.

The instrument 400 can be used as a first category, first classinstrument. It includes an elongated, tapered shank 405 with superficialtransversally striated grooves 410 with slightly cutting edges that areseparated by smooth areas 411, according to a preferred embodiment ofthe present invention. In one exemplary embodiment, the grooves 410 formshort, transversally linear striations that are approximately 1 mm inwidth. The distance between two consecutive grooves 410 may be adjustedso that it can be either fixed or variable, along the axial length ofthe shank 405. As an example only, the separation of the grooves 410(which constitutes the width of the smooth areas 411) can vary betweenapproximately 2 mm and 3 mm.

The instrument 400 further includes a pointed, beveled cutting tip 420and a handle 125.

FIG. 5 illustrates an exemplary hand operated instrument 500 that isgenerally similar in design and construction to the instrument 300 ofFIG. 3A. It should be understood that the instrument 500 can bemodified, as explained herein, for use as an electrically rotatinginstrument.

The instrument 500 can be used as a first category, first classinstrument. It includes an elongated, tapered shank 505 with superficialtransversally striated grooves 510 with slightly cutting edges that areseparated by roughened areas 511, according to a preferred embodiment ofthe present invention. In one exemplary embodiment, the grooves 510 formshort, transversally linear striations.

In a most preferred embodiment, the roughened areas 511 are formed bysandblasting. The instrument 500 further includes a cutting ornon-cutting tip 520 and a handle 125.

FIG. 6 illustrates an exemplary hand operated instrument 600 that isgenerally similar in design and construction to the instrument 350 ofFIG. 3B. It should be understood that the instrument 600 can bemodified, as explained herein, for use as an electrically rotatinginstrument.

The instrument 600 can be used as a first category, second classinstrument. It includes an elongated, tapered shank 605 with deeptransversally striated grooves 610 with cutting edges that are separatedby restricted smooth areas 611, according to a preferred embodiment ofthe present invention. In one exemplary embodiment, the grooves 610 formshort, transversally linear striations that are approximately 2 to 3 mmin width. The separation distance between the grooves 610 may beadjusted so that it can be either fixed or variable, along the axiallength of the shank 605. As an example only, the separation of thegrooves 610 (which constitutes the width of the smooth areas 611) is 1mm.

The instrument 600 further includes a pointed, cutting or non-cuttingtip 620 and a handle 125.

2^(nd) Category: Instruments for Penetrating Fine and Curved Root Canals

As illustrated in FIG. 7, this category comprises electrically operatedrotating instruments (e.g., 700) that are preferably (but notexclusively) made for example of NiTi, from No. 10 to 20, with a shank705 having a taper of approximately 2%. Although the illustratedinstrument 700 is shown to include a series of transversal, deep,striated grooves 710 with cutting edges, it should be understood thatother embodiments can alternatively include a series of horizontally orvertically striated, deep grooves with cutting edges, that are separatedby either smooth or roughened (i.e., sandblasted) restricted areas 711,or even instruments that are completely sandblasted.

The shank 705 of the instrument 700 has a generally circularcross-section, and a conical cutting or non-cutting tip 720, with alength ranging from approximately 21 to 32 mm. The circular crosssection and conical tip 720 of the shank 705 helps create a space aroundthe segment(s) of the fractured instruments that are lodged within theroot canal, thus enabling the instruments of the 1^(st) category, 1^(st)class, to bypass the lodged fractured segment(s).

A handle 725 secures the shank 705 to an external motorized source (notshown).

3^(rd) Category: Instruments which May be Used for Enlarging and ShapingRoot Canals

As illustrated in FIG. 8, this category comprises electrically operatedrotating instruments (e.g., 800) made of NiTi from No. 20 to 40, with ashank 805 having a generally circular cross section. Although theillustrated instrument 800 is shown to include a conical cutting ornon-cutting tip 820, with a series of saw teeth 810 that are separatedby restricted smooth areas 811, it should be understood that otherembodiments can further include horizontally, vertically, ortransversally striated grooves.

The saw teeth configuration expels the dental debris from the root canaland lessens the rubbing force of the instrument on the walls of the rootcanal, especially when using files from Nos. 20 to 40, thus avoidingroot canal cracks.

The taper of the shank 805 ranges from approximately 4% to 10%, and hasa length of approximately 21 mm to 32 mm.

It is important to note that the shanks of the instruments in all theforegoing three categories may or may not be sandblasted. It is alsonoteworthy to indicate that the instruments of the above threecategories successfully penetrate root hypercalcifications that areformed in the root canal. In addition, a file instrument No. 20 with a4% taper, and a file instrument No. 17 with a 4% taper, have shownremarkable utility in creating a space around fractured, lodgedfragments of previously used instruments, so that the instruments of the1^(st) category, 1^(st) class, may be used in order to bypass thesefractured instruments.

Alternative embodiments that are contemplated by the present inventioninclude but are not limited to the following hand operated andelectrically operated instruments:

FIGS. 9A, 9B illustrate an electrically operated instrument 900 and amanually operated instrument 950 that is generally similar in design andfunction to the electrically operated instrument 900, and therefore onlyone instrument will be described in detail. The electrically operatedinstrument 900 generally includes an elongated, tapered shank 905 thatdefines an upper cylindro-conical section 910 and a spirally (orhelically) shaped lower section 915.

The cylindro-conical section 910 includes at its upper end, a tip 920that may be cutting or non-cutting, depending on the desiredapplication. While in this particular illustration the cylindro-conicalsection 910 is illustrated as being a roughened surface, it should beunderstood that the cylindro-conical section 910 could include striatedgrooves with cutting edges separated by smooth or sandblasted areas. Thelength of the shank 905 preferably ranges between approximately 12 mmand 32 mm, and its width preferably varies from No. 10 to 40. The taperof the instrument preferably ranges from approximately 2% to 10%. In apreferred embodiment, the entire shank 905 of the instrument 900 issandblasted.

Section 910 is intended to penetrate root canal blockages while section915 serves to debride and to shape the opened path.

The instrument 900 further includes a handle 925 that secures one end ofthe shank 905, and that enables an endodontist to connect the instrument900 to an external rotary source (not shown) as is known or available inthe field. Similarly, the instrument 950 further includes a manualhandle 955 that secures one end of the shank 905, and that enables anendodontist to safely and ergonomically hold the instrument 950 whilemanually performing the treatment.

FIGS. 10A, 10B illustrate an electrically operated instrument 1000, anda manually operated instrument 1050 that is generally similar in designand function to the electrically operated instrument 1000, and thereforeonly one instrument will be described in detail. The electricallyoperated instrument 1000 generally includes an elongated, tapered shank1005 that defines a plurality of roughened cylindro-conical sections1010, 1011, 1012, that are separated by a plurality of spirally (orhelically) shaped sections 1015, 1016.

The cylindro-conical section 1010 of the instrument 1000 comprisestriated grooves with cutting edges separated by smooth or sandblastedareas and further includes at its forwardmost end, a tip 1020 that maybe cutting or non-cutting, depending on the desired application. Thelength of the shank 1005 ranges from approximately 12 mm to 32 mm, andits width preferably varies from No. 10 to 40. The taper of theinstrument preferably ranges from approximately 2% to 10%. In apreferred embodiment, the whole instrument will be sandblasted.

Section 1010 is intended to penetrate root canal blockages while section1015 serves to debride and to shape the opened path.

The instruments illustrated in FIG. 10 provide better penetrationresults than the instruments in FIG. 9. They are preferred in case ofhard hypercalcifications and resistant paste.

FIGS. 11A, 11B respectively illustrate an electrically operatedinstrument 1100, and a manually operated instrument 1150 that isgenerally similar in design and function to the electrically operatedinstrument 1100, and therefore only one instrument will be described indetail. The electrically operated instrument 1100 generally includes anelongated, tapered shank 1105 that defines a plurality of roughenedcylindro-conical sections 1110, 1111, which are separated by a pluralityof spirally (or helically) shaped sections 1115, 1116, 1117.

The spiral section 1115 of the instrument 1100 further includes at itsforwardmost end, a tip 1120 that may be cutting or non-cutting,depending on the desired application. The length of the shank 1105ranges from approximately 12 mm to 32 mm, and its width preferablyvaries from No. 10 to 40. The taper of the instrument preferably rangesfrom approximately 2% to 10%.

In the exemplary embodiment of FIG. 11, the cylindro-conical sections1110, 1111 may be striated with groves with cutting edges separated bysmooth or sandblasted areas. In a preferred embodiment, the wholeinstrument will be sandblasted.

FIGS. 12A, 12B illustrate yet other alternative embodiments of anelectrically operated instrument 1200 and a manually operated instrument1250, that are respectively, generally similar in design and function tothe instruments 1000, 1050 of FIGS. 10A, 10B.

The electrically operated instrument 1200 generally includes anelongated, tapered shank 1205 that defines a plurality of roughenedcylindro-conical sections 1210, 1211, 1212, that are separated by aplurality of spirally (or helically) shaped sections 1215, 1216. Thecylindro-conical section 1210 of the instrument 1200 further includes atits forwardmost end, a tip 1220 that may be cutting or non-cutting,depending on the desired application. The length of the shank 1205ranges from approximately 12 mm to 32 mm, and its width preferablyvaries from No. 10 to 40. The taper of the instrument preferably rangesfrom approximately 2% to 10%.

In the exemplary embodiment of FIG. 12, the cylindro-conical sections1210, 1211, 1212 may be striated with groves with cutting edgesseparated by smooth or sandblasted areas while the spiral sections maybe similarly sandblasted.

Having described the exemplary instruments embodied by the presentinvention, the methods of using these instruments will now be describedin more detail, in connection with the drawings, particularly FIGS. 13through 18.

Methods of Using the Instruments in Treating Root Canals

The new root canal treatment method generally aims to bypass rootobstructions resulting from fractured instruments and to penetratehypercalcification, to bypass dental shoulders, to penetrate resistantpaste, curved root canals and other obstructions resulting from aprevious root treatment. More specifically, the following exemplarytreatment methods will now be described in more detail:

I—Method of treating a root canal that does not exhibit signs of aresistive path, obstruction, or blockage.II—Method of bypassing root obstructions resulting from fracturedinstruments.III—Method of penetrating root obstructions resulting fromhypercalcification.IV—Method of penetrating root obstructions resulting from curved rootcanals.V—Method of bypassing root obstructions resulting from a shoulder.VI—Method of penetrating root obstructions resulting from a previousroot canal treatment.

I—Method of Treating a Root Canal that does not Exhibit Signs of aResistive Path, Obstruction, or Blockage

FIG. 13 comprises FIGS. 13A, 13B, 13C, and 13D and illustrates anexemplary tooth 1300 that does not exhibit signs of a resistive path,obstruction, or blockage. With further reference to FIG. 18, anendodontic treatment method 1800 is performed according to the followingsteps:

As illustrated in FIG. 13A, the endodontist starts at step 1810 of FIG.18, to enlarge the root canal 1312 by selectively and sequentially usingthe instruments (denoted with numeral reference 1320) of the 1^(st)category, 2^(nd) class (e.g., FIGS. 1B, 2B, 3B and 6), starting forexample with a manual instrument No. 8 having an approximate 2% taper,in increasing order to No. 15 with an approximate 2% taper (1^(st)category, 2^(nd) class), exerting a manual force with a clockwise90-degree rotation along the arrow F, in order to reach the apex 1333 ofthe root canal 1312.

As illustrated at step 1820 of FIG. 18, the endodontist further enlargesthe root canal 1312 using for example, an electrically rotatinginstrument (denoted with numeral reference 1330) selected from the2^(nd) category (e.g., FIG. 7), starting with No. 10 having anapproximate 2% taper, in an increasing order to No. 20, along the arrowF in order to reach the apex of the root canal 1333.

As illustrated at step 1830 of FIG. 18 and in FIG. 13B, the endodontistcontinues to enlarge the root canal 1312 using for example, anelectrically rotating instrument 1320, which is selected from the 3rdcategory (e.g., FIG. 8), starting with an instrument from No. 20 to No.25 with an approximate 4% taper to No. 25 with an approximate 6% taperwhenever possible, in order to reach the apex 1333 of the root canal1312. In a preferred embodiment, an instrument with No. 20 having anapproximate 4% taper can be used.

As illustrated at step 1840 and also in FIG. 13C, upon completion ofstep 1830 as described earlier, the endodontist clears the widened rootcanal 1312 of any debris, as is known in the field, in preparation forthe final obturation step.

As illustrated at step 1850 and also in FIG. 13D, the endodontistobturates the root canal 1312 with the appropriate filling material1350, as is known in the field.

II—Method of Bypassing Root Obstructions Resulting from FracturedInstruments

With reference to FIG. 14, it comprises FIGS. 14A, 14B, 14C, 14D, 14E,and 14F, and illustrates an exemplary tooth 1400 having a root canal1412 within which an obstruction, such as a fragment 1410 of a fracturedinstrument (such as a file) is lodged by a previous root canaltreatment. With further reference to FIGS. 19A and 19B, the treatmentmethod 1900 is performed according to the following steps:

As further illustrated in FIG. 14A, at step 1910 of FIG. 19A, theendodontist enlarges the root canal 1412 by selectively and sequentiallyusing the instruments (denoted with numeral reference 1420) of the1^(st) category, 2^(nd) class (e.g., FIGS. 1B, 2B, 3B and 6), startingfor example with a manual instrument No. 8 having an approximate 2%taper, in increasing order to No. 15 with an approximate 2% taper(1^(st) category, 2^(nd) class), exerting a manual force with aclockwise 90 degrees rotation in along the arrow F, in order to reachthe fractured instrument 1410 of the root canal 1412.

As illustrated at step 1920 of FIG. 19A and also in FIG. 14B, theendodontist further enlarges the root canal 1412 using for example, anelectrically rotating instrument (denoted with numeral reference 1430)selected from the 2^(nd) category (e.g., FIG. 7), starting with No. 10having an approximate 2% taper, in an increasing order to No. 20, inorder to reach the fractured instrument in the root canal 1412.

As illustrated at step 1930 of FIG. 19A and also in FIG. 14B, theendodontist continues to enlarge the root canal 1412 using for example,an electrically rotating instrument (denoted with numeral reference1430) selected from the 3^(rd) category (e.g., FIG. 8), starting with aninstrument from No. 20 to No. 25 with an approximate 4% taper to No. 25with an approximate 6% taper whenever possible. In a preferredembodiment, an instrument with No. 20 having an approximate 4% taper canbe used to reach the fractured instrument in the root canal 1412.

For relatively simple cases, each new instrument (whether manual orelectrically operated) is capable of bypassing the obstruction afterenlarging the root canal 1412 according to above steps 1910, 1920, and1930.

However, for more complex cases, and as illustrated by step 1940 of FIG.19A and FIG. 14C, the endodontist resumes process 1900 by engraving acutting 1444 beside the obstruction 1410, using new manual instruments,selected for example from the 1^(st) category, 1^(st) class, andpreferably made of NiTi, No. 20, with an approximate 4% taper and acutting tip (e.g., 120, 220, 320, 520 or eventually 420). Theendodontist starts by exerting a manual force with a clockwise 90-degreerotation, and then withdraws the instrument by exerting ananti-clockwise rotation of the same angle, along the rotational arrow M.The relatively large cross sectional surface of the cutting tip 120,220, 320, 520 or eventually 420 avoids opening a false canal whenexerting a relatively high manual force.

The endodontist then enlarges the cutting 1444 into an initial pathusing a manual instrument (also denoted by the numeral reference 1440)selected for example from the 1^(st) category, 1^(st) class, andpreferably made of NiTi, No. 20 with an approximate 4% taper and anon-cutting tip (e.g. 1633 B), exerting a manual force with a clockwise90 degrees rotation along the arrow F, in order to preserve the initialpath 1444.

As further illustrated in FIG. 14D, and in order to further penetratethe obstructed canal through the opened initial path 1444, theendodontist uses, at step 1960 of FIG. 19B, a manual instrument 1450selected for example from the 1^(st) category, 1^(st) class, andpreferably made of stainless steel, No. 20, having an approximate 2%taper with a cutting tip (e.g., 1633 A), for engraving a new cutting1445, adjacent to the obstruction 1410, exerting a manual force with aclockwise 90-degree rotation along the arrow F.

Thereafter, the endodontist preferably uses, at step 1970 of FIG. 19B,to manually enlarge the newly opened cutting 1445 using an instrument(still denoted by 1450) selected for example from the 1^(st) category,1^(st) class, and preferably made of stainless steel, No. 20, having anapproximate 2% taper with a non-cutting tip (e.g., 1633 B).

The endodontist continues to enlarge the new path 1445 using a manualinstrument (still denoted by 1450) selected for example from the 1^(st)category, 1^(st) class, and preferably made of NiTi, No. 20, having anapproximate 4% taper with a cutting tip (e.g., 1633 A), followed by No.20 having an approximate 4% taper with a non-cutting tip (e.g., 1633 B),in order to preserve the new path 1445.

In case the endodontist encounters difficulty in penetrating the rootcanal 1412, and whenever suitable, the endodontist may use a manualinstrument 1440 (FIG. 14C) selected for example from the 1^(st)category, 1^(st) class, and preferably made of stainless steel, No. 20,having an approximate 2% taper with a cutting tip (e.g., 1633 A),followed by No. 20 having an approximate 2% taper with a non-cutting tip(e.g., 1633 B).

Alternatively, the endodontist may use a manual instrument 1450 (FIG.14D) selected for example from the 1^(st) category, 1^(st) class, andpreferably made of stainless steel, No. 15, having an approximate 2%taper with a cutting tip (e.g., 1633 A) in order to create a newcutting. This step is then followed by the use of a manual instrumentselected for example from the 1^(st) category, 1^(st) class, andpreferably made of stainless steel, No. 15, having an approximately 2%taper with a non-cutting tip (e.g., 1633 B), in order to preserve thenewly opened path 1445.

In the event the instruments that are collectively referenced by 1450fail to open or enlarge the required path 1445, the endodontist uses asmaller instrument preferably made of stainless steel, in the samesequence as described above, until the apex 1466 of the root canal 1412is reached (step 1980), as follows: The path 1445 is enlarged manually,at step 1970, using sequentially hand operated stainless steelinstruments with cutting and non-cutting tips from No. 8 or 10 until No.20 of approximately 2% taper (1^(st) category 1^(st) class). Theintroduction of the instrument with a cutting tip is followed by the useof the same instrument with a non-cutting tip. Alternatively, use may bemade of NiTi instrument 1450, No. 20 with an approximate 4% taper(1^(st) category, 1^(st) class), first with instrument 1450 having acutting tip (e.g., 1633 A), then with instrument 1450 having anon-cutting tip (e.g., 1633 B).

The endodontist starts at step 1980 with electrically operatedinstruments of the 1^(st) category, 1^(st) class, which are preferablymade of NiTi, and having a non-cutting tip (e.g., 1633 B), in anincreasing order starting by using instrument no. 10 with approximately2% taper until reaching No. 20 of approximately 2% taper.

Then, the endodontist continues with electrically operated instrumentsof the 2^(nd) category, which are preferably made of NiTi, and having anon-cutting tip (e.g., 1633 B), in an increasing order instruments fromNo. 20 to No. 25 having approximately 2% taper.

Finally, the endodontist completes the enlargement of the path 1445 withelectrically operated instruments of the 3^(rd) category, which arepreferably made of NiTi, and having a non-cutting tip (e.g., 1633 B),namely instrument No. 20 or 25 having approximately 4% taper.

It should be noted that the use of files (or instruments) having abeveled tip is recommended only in case the aforesaid instruments failto engrave a cutting or path adjacent to the fractured instrument 1410,particularly in case of difficult hypercalcification cases or in thecase the cross section of the fractured instrument 1410 is relativelylarge.

As illustrated at step 1990 and also in FIG. 14E, upon completion ofstep 1980 as described earlier, the endodontist clears the widened rootcanal 1445 of any debris, as is known in the field, in preparation forthe final obturation step.

As illustrated at step 1999 and also in FIG. 14F, the endodontistobturates the root canal 1445 with the appropriate filling material1446, as is known in the field. It should be noted that the obturationmay be performed with or without removing the fragment 1410 of thefractured instrument.

Although the conventional art describes that the use of electricallyoperated files may not be proper in case of treating dental roots withfractured instruments 1410, the present invention teaches that it ispossible to directly reach the apex 1466, at step 1999, by usingelectrically operated instruments with non-cutting tips, made of NiTi,after step 1970, in an increasing order from No. 10 with an approximate2% taper (selected from the 1^(st) category, 1^(st) class) to No. 20with an approximate 4% taper (selected from the 1^(st) category, 1^(st)class), followed by the sequential use of instruments selected from the2^(nd) and 3^(rd) categories, as deemed appropriate by the endodontist.

Alternatively, the present invention teaches that in less difficultcases, it is possible from step 1950 to directly reach the apex 1466,step 1999, by using electrically operated instruments with non-cuttingtips, made of NiTi, starting by enlarging the initial path 1444 with No.20 having an approximate 4% taper (1^(st) category, 1^(st) class); thenusing in an increasing order NiTi instruments with non-cutting tip fromNo. 10 with an approximate 2% taper (selected from the 1^(st) category,1^(st) class) to No. 20 with an approximate 4% taper (selected from the1^(st) category, 1^(st) class), followed sequentially by instrumentsselected from the 2^(nd) and 3^(rd) categories, as deemed appropriate bythe endodontist.

It is worth noting that the root canal is irrigated with sodiumhypochloride and EDTA (Ethylenediaminetetraacetic acid) at each relevantstep of process 1900.

The following X-Rays FIGS. 23A, 23B, 23C, 24A, 24B, 24C, 25A, 25B, 25C,25D, 26A, 26B, 27A, 27B, 27C, 28A, 28B, 28C, 28D, 29A, 29B, 29C, 30A,30B, 31A, 31B, 32A, 32B, 32C, 33A, 33B, 33C, 33D, 34, 35, 36A, 36B, 36C,37A, 37B, 38A, and 38B provide supporting illustrations of this novelprocess 1900:

FIG. 23A shows a broken file in tooth no. 26 blocking the totality ofthe root canal. FIG. 23B shows the bypassing of the broken file andreaching the apex with the new instrument according to the presentinvention. FIG. 23C shows the fully hermetic obturation of the treatedroot canal.

FIG. 24A shows a broken file in tooth no. 46 blocking the totality ofthe root canal. FIG. 24B shows the bypassing of the broken file and thepiercing of the hypercalcification and reaching the apex with the newinstrument according to the present invention. FIG. 24C shows the fullyhermetic obturation of the treated root canal.

FIG. 25A shows a hypercalcification, a shoulder, and a broken file inthe mesial canals of tooth no. 36. FIG. 25B shows the broken file. FIG.25C shows the bypassing of the broken file, the penetration of theshoulder and the piercing of the hypercalcification in the 2^(nd) mesialcanal and reaching the apex with the new instrument, according to thepresent invention. FIG. 25D shows the fully hermetic obturation of thetreated root canal.

FIG. 26A shows two fractured files in the mesio vestibular canal intooth no. 46, blocking the totality of the root canal. FIG. 26B showsthe bypassing of the two broken files and reaching the apex with the newinstrument according to the present invention.

FIG. 27A shows three broken files in tooth no. 35 blocking the totalityof the root canal. FIG. 27B shows the bypassing of the three brokenfiles and reaching the apex with the new instrument according to thepresent invention. FIG. 27C shows the fully hermetic obturation of theroot canal.

FIG. 28A shows a broken file in tooth no. 47 blocking the totality ofthe root canal due to hypercalcification. FIG. 28B shows a cutting madewith the new instrument according to the invention, and a second brokenfile. FIG. 28C shows the bypassing of the two broken files and thepiercing of the hypercalcification and reaching the apex with the newinstrument according to the present invention. FIG. 28D shows the fullyhermetic obturation of the treated root canal.

More specifically, and as a comparative illustration, instead of usingthe new instruments according to the invention, a conventional file wasused to enlarge the cutting and to bypass the broken file. However, theconventional file was broken, as expected, while the new instrumentaccording to the invention has successfully bypassed the two brokenfiles, pierced the hypercalcification, and reached the apex, withoutmaking a false canal (FIG. 28C).

FIG. 29A shows two superposed broken files in tooth no. 26 blocking thethird apical of the root canal. FIG. 29B shows the bypassing of thebroken files and reaching the apex with the new instrument according tothe present invention. FIG. 29C shows the fully hermetic obturation ofthe treated root canal.

FIG. 30A shows a broken file in tooth no. 37 blocking the third apicalof the root canal. FIG. 30B shows the bypassing of the broken file andreaching the apex with the new instrument according to the presentinvention.

FIG. 31A shows a false canal and two broken files in tooth no. 36blocking the apex of the root canal. FIG. 31B shows the avoidance of thefalse canal and the bypassing of the broken file and reaching the apexwith the new instrument according to the present invention.

FIG. 32A shows a broken file in the third apical of the mesial canaltooth no. 46 blocking the apex. FIG. 32B shows the bypassing of thebroken file and reaching the apex with the new instrument according tothe present invention. FIG. 32C shows the fully hermetic obturation ofthe treated root canal.

III—Method of Penetrating Root Obstructions Resulting fromHypercalcification

With reference to FIG. 15, it comprises FIGS. 15A, 15B, and 15C andillustrates an exemplary tooth 1500 having a root canal 1512 that isblocked or obstructed by hypercalcification 1510. With further referenceto FIGS. 20A, 20B, the treatment method 2000 is performed according tothe following steps:

As further illustrated in FIG. 15A, the endodontist enlarges, at step2010 of FIG. 20A, the root canal 1512 of the tooth 1500 by starting witha manual instrument selected from the 1^(st) category, 2^(nd) class, No.8, with an approximate 2% taper, in an increasing order to an instrumentselected from the 1^(st) category, 2^(nd) class, No. 15, with anapproximate 2% taper, exerting a manual force with a clockwise 90-degreerotation along the arrow F, until the tip 1525 of the instrument 1520reaches the hypercalcification 1510.

The endodontist then further enlarges, at step 2020, the root canal 1512using electrically rotating instruments 1520 selected from the 2^(nd)category, starting with No. 10 with an approximate 2% taper, in anincreasing order to No. 20 with an approximate 2% taper, until reachingthe hypercalcification.

Still at step 2020, the endodontist continues to enlarge the root canal1512 using electrically rotating new instruments that are selected fromthe 3^(rd) category, using files from No. 20 to No. 25 with anapproximate 4% taper, to No. 25 with an approximate 6% taper wheneverpossible. Preferred results were obtained with a No. 20 instrument withan approximate 4% taper, until reaching the hypercalcification 1510.

The endodontist then starts piercing the hypercalcification 1510 at step2030, to form an initial path 1555 therewithin, using manual NiTiinstruments 1530 selected from the 1^(st) category, 1^(st) class, No. 20with an approximate 4% taper, and a cutting tip 1525. The endodontistexerts a manual force with a clockwise 90-degree rotation. Theendodontist then withdraws the instrument 1530 by exerting ananti-clockwise rotation of the same angle. The relatively largecross-sectional surface of the cutting tip 1525 avoids opening a falsecanal when exerting a relatively high manual force.

The endodontist continues at step 2040 by enlarging the initial path1555, using a manual NiTi instrument that is selected from the 1^(st)category, 1^(st) class, No. 20 having an approximate 4% taper with anon-cutting tip (e.g., 1633 B), in order to preserve the opened initialpath 1555.

The endodontist then continues to step 2050, in order to enlarge theinitial path 1555 and to pierce the remainder of the hypercalcification,by using a manual stainless steel instrument selected from the 1^(st)category, 1^(st) class, No. 20, with an approximate 2% taper and acutting tip 1525. It is recommended to continue to manually enlarge theinitial path 1555 using a manual stainless steel instrument selectedfrom the 1^(st) category, 1^(st) class, No. 20 with an approximate 2%taper and a non-cutting tip (e.g., 1633 B).

At step 2060, the endodontist further enlarges the initial path 1555 byfirst using a manual NiTi instrument selected from the 1^(st) category,1^(st) class, No. 20, with an approximate 4% taper and a cutting tip1555, and then using a manual NiTi instrument also selected from the1^(st) category, 1^(st) class, No. 20, with an approximate 4% taper anda non-cutting tip (e.g., 1633 B), so as to preserve the initial path1555.

In the event the endodontist encounters difficulty in penetrating theroot canal 1512, manual stainless steel instrument 1540 selected fromthe 1^(st) category, 1^(st) class, No. 20, with an approximate 2% taperand a cutting tip 1525 is used whenever feasible. Otherwise, theendodontist uses a manual stainless steel instrument 1540 selected fromthe 1^(st) category, 1^(st) class, No. 15, with an approximate 2% taperand a cutting tip 1525, in order to pierce a new path that is adjacentto the initial path 1555. This step is followed by the use of a manualstainless steel instrument 1540 selected from the 1^(st) category,1^(st) class, No. 15, with an approximate 2% taper and a non-cuttingtip, in order to preserve the new adjacent path. In case the instruments1540 fail to open the required path, the endodontist uses smallerstainless steel instruments in the same sequence until reaching the apex1566 of the root canal 1512 (FIG. 15C).

Once the initial path 1555 is enlarged, at step 2060, the initial path1555 is gradually enlarged manually using sequentially hand operatedstainless steel instruments with cutting and non-cutting tips from No. 8or 10 until No. 20 of approximately 2% taper (1^(st) category 1^(st)class). The introduction of the instrument with a cutting tip isfollowed by the use of the same instrument with a non-cutting tip.Alternatively, if possible, a NiTi instrument also selected from the1^(st) category, 1^(st) class, No. 20 with an approximate 4% taper and acutting tip 1525 followed by the same instrument with a non-cutting tip(e.g., 1633 B), may be introduced.

Once the initial path 1555 has been enlarged to the desired dimensions,the endodontist then uses, at step 2070, electrically operated NiTiinstruments 1540 selected from the 1^(st) category, 1^(st) class, andinstruments of the 2^(nd) category, with a non-cutting tip (e.g., 1633B), followed by the use of instruments 1540 of the 3^(rd) category, witha non-cutting tip. In performing this step 2070, the endodontistsequentially uses in increasing order the instruments 1540 starting withinstruments selected from the 1^(st) category, 1^(st) class, No. 10 toNo. 20 with an approximate 2% taper, and then, instruments from No. 20to No. 25 of approximately 2% taper of the 2^(nd) category and finallyinstrument No. 20 or 25 with an approximate 4% taper of the 3^(rd)category at the apex 1566.

As illustrated at step 2080 and also in FIG. 14E, upon completion ofstep 2070 as described earlier, the endodontist clears the widened rootcanal of any debris, as is known in the field, in preparation for thefinal obturation step.

As illustrated at step 2090 and also in FIG. 14F, the endodontistobturates the root canal with the appropriate filling material 1446, asis known in the field.

According to the another embodiment of the present invention, it ispossible to directly reach the apex 1566, after step 2060, by usingelectrically operated NiTi instruments selected from the 1^(st)category, 1^(st) class with a non-cutting tip (e.g., 1633 B), inincreasing order from No. 10 with an approximate 2% taper to No. 20 withan approximate 4% taper, followed by instruments of the 2^(nd) and3^(rd) categories.

According to yet another embodiment of the present invention, in lessdifficult cases, the endodontist may be able to directly reach the apex1566, after step 2040, by using electrically operated NiTi instrumentsselected from the 1^(st) category, 1^(st) class with a non-cutting tip(e.g., 1633 B), starting by enlarging the piercing with a No. 20instrument having an approximate 4% taper. The process is resumed byusing, in increasing order, instruments selected from the 1^(st)category, 1^(st) class, from No. 10 with an approximate 2% taper, to No.20 with an approximate 4% taper of the 1^(st) category, 1^(st) classwith a non-cutting tip, followed by non-cutting tip instruments of the2^(nd) and 3^(rd) categories, as deemed appropriate by the endodontist.

It is worth noting that the root canal is irrigated with sodiumhypochloride and EDTA (Ethylenediaminetetraacetic acid) at each relevantstep of process 2000.

The following X-Rays (FIGS. 33 through 36) provide supportingillustrations of this novel process 2000:

FIG. 24A shows a broken file in tooth no. 46 blocking the totality ofthe root canal. FIG. 24B shows the bypassing of the broken file and thepiercing of the hypercalcification and reaching the apex with the newinstrument according to the present invention. FIG. 24C shows the fullyhermetic obturation of the treated root canal.

FIG. 33A shows an incomplete root treatment of tooth no. 35 due tohypercalcification blocking the third apical of the root canal. FIGS.33B, 33C, and 33D show the piercing of the old resistant paste andprogressively piercing the hypercalcification with the new instrumentreaching the apex, according to the present invention.

FIG. 34 shows a fully hermetic obturation of tooth no. 46 after piercinga hypercalcification and passing through an accentuated curved line.

FIG. 35 shows a fully hermetic obturation of tooth no. 47 after piercinga hypercalcification and passing through an accentuated curved line.

FIG. 36A shows a false canal and an incomplete root treatment of toothno. 35 due to hypercalcification blocking about half the root canal.FIGS. 36B and 36C show the progressive piercing of thehypercalcification with the new instrument reaching the apex, accordingto the present invention.

IV—Method of Penetrating Root Obstructions Resulting from Curved RootCanals

As illustrated in FIG. 13, the instruments of the present invention maybe used to penetrate root obstructions resulting from curved rootcanals. In this event, the instruments of the 2^(nd) category may beused followed by the instruments of the 3^(rd) category, until the apexof the root canal is reached, with at least an instrument No. 20 havingan approximate 4% taper. In case of difficulty, instruments selectedfrom the 1^(st) category, 2^(nd) class are used, starting in increasingorder from No. 8 to No. 15, with an approximate 2% taper followed by theinstruments of the 2^(nd) and 3^(rd) categories.

The following X-Rays (FIGS. 34, 35) provide supporting illustrations ofthis novel process:

FIG. 34 shows a fully hermetic obturation of tooth no. 46 after piercinga hypercalcification and passing through an accentuated curved line.

FIG. 35 shows a fully hermetic obturation of tooth no. 47 after piercinga hypercalcification and passing through an accentuated curved line.

V—Method of Bypassing Root Obstructions Resulting from a Shoulder

With reference to FIG. 16, it comprises FIGS. 16A, 16B, and 16C andillustrates an exemplary tooth 1600 having a root canal 1612 that isobstructed by a shoulder 1610. With further reference to FIGS. 21A and21B, the treatment method 2100 is performed according to the followingsteps:

As further illustrated in FIG. 16A, the endodontist enlarges at step2110 of FIG. 21A, the root canal 1612 of the tooth 1600 by using amanual instrument selected from the 1^(st) category, 2^(nd) class, No. 8with an approximate 2% taper, in increasing order to No. 15 with anapproximate 2% taper, in order to reach the shoulder 1610. For thepurpose of illustration only, FIG. 16A shows an enlarged view of acutting tip 1633A, while FIG. 16C shows an enlarged view of anon-cutting tip 1633B.

The endodontist then, at step 2120, further enlarges the root canal 1612using electrically rotating instruments selected from the 2^(nd)category, starting with files No. 10 and an approximate 2% taper, in anincreasing order to No. 20 with an approximate 2% taper, up to theshoulder 1610.

The endodontist continues to enlarge the root canal 1612 at step 2120,using electrically rotating instruments selected from the 3^(rd)category, starting with files No. 20 to 25 with an approximate 4% taper,and continuing with files No. 25 with an approximate 6% taper, wheneverpossible, until the shoulder 1610 is reached. Preferred results wereobtained with a No. 20 instrument with an approximate 4% taper.

Once the portion of the root canal 1612 up to the shoulder 1610 has beenwidened to the desired dimensioned, the endodontist continues at step2130 by creating a path 1655 through the shoulder 1610 using manual NiTiinstruments 1620 selected from the 1^(st) category, 1^(st) class, No. 20with an approximate 4% taper and a cutting tip 1633, by exerting amanual force in a push and pull motion along the arrow F. Thereafter,the instrument 1620 is withdrawn. The relatively large cross sectionalsurface of the cutting tip 1633A avoids opening a false canal whenexerting a relatively high manual force.

At step 2140, the endodontist enlarges the path 1655 using a manual NiTiinstrument selected from the 1^(st) category, 1^(st) class, No. 20having an approximate 4% taper and a non-cutting tip 1633B in order topreserve the opened path 1655.

In case of difficulty in enlarging the path 1655, the endodontist uses amanual stainless steel instrument selected from the 1^(st) category,1^(st) class, No. 20 having an approximate 2% taper with a cutting tipto penetrate the shoulder 1610 in a push and pull motion. Thereafter, itis recommended to manually enlarge the newly opened path 1655 using amanual stainless steel instrument selected from the 1^(st) category,1^(st) class, No. 20 having an approximate 2% taper with a non-cuttingtip 1633B.

Still at step 2140, the endodontist continues to enlarge the path 1655using a manual NiTi instrument selected from the 1^(st) category, 1^(st)class, No. 20 having an approximate 4% taper and a cutting tip 1633. Amanual NiTi instrument selected from the 1^(st) category, 1^(st) class,No. 20 and an approximate 4% taper with a non-cutting tip 1633B, may beused in order to preserve the newly opened path 1655.

In case of difficulty in penetrating the shoulder 1610, the endodontistuses a manual stainless steel instrument 1620 selected from the 1^(st)category, 1^(st) class, No. 15 having an approximate 2% taper and acutting tip 1633, in order to penetrate the shoulder 1610. This step isfollowed by the use of a manual stainless steel instrument 1620 selectedfrom the 1^(st) category, 1^(st) class, No. 15 having an approximate 2%taper with a non-cutting tip 1633B, in order to preserve the newlyopened path 1655. In case the abovementioned instruments 1620 fail toopen the required path 1655, the endodontist may use smaller stainlesssteel instruments 1620 in the same sequence until reaching the apex1650.

Still at step 2140, the endodontist further enlarges the opened path1655 manually until the introduction of stainless steel instrumentsselected from the 1^(st) category, 1^(st) class, No. 20 with anapproximate 2% taper (alternatively NiTi instrument No. 20 with anapproximate 4% taper) having a cutting tip 1633A and then a non-cuttingtip 1633B, is made possible.

As further illustrated in FIG. 16C, once the path 1655 has been enlargedto the desired dimensions, the endodontist then uses, at step 2150,electrically operated NiTi instruments 1630 selected from the 1^(st)category, 1^(st) class, 2^(nd) category, with a non-cutting tip 1633B,followed by the use of a non-cutting tip instrument 1630 of the 3^(rd)category. In performing this step 2150, the endodontist sequentiallyuses, in increasing order, the instruments 1630 starting withinstruments selected from the 1^(st) category, 1^(st) class, No. 10 toNo. 20 with an approximate 2% taper, and then instruments from No. 20 toNo. 25 of the 2^(nd) category and finally instrument No. 20 or 25 withan approximate 4% taper of the 3^(rd) category at the apex 1650.

As illustrated at step 2160 and also in FIG. 14E, upon completion ofstep 2140 as described earlier, the endodontist clears the widened rootcanal of any debris, as is known in the field, in preparation for thefinal obturation step.

As illustrated at step 2170 and also in FIG. 14F, the endodontistobturates the root canal with the appropriate filling material 1446, asis known in the field.

According to the another embodiment of the present invention, it ispossible to directly reach the apex 1650, following step 2140, by usingelectrically operated instruments selected from the 1^(st) category,1^(st) class, provided with non-cutting tips, in an increasing orderfrom files No. 10 with an approximate 2% taper to files No. 20 with anapproximate 4% taper, followed by instruments of the 2^(nd) and 3^(rd)categories as deemed appropriate by the endodontist.

According to yet another embodiment of the present invention, in lessdifficult cases, after enlarging the path 1655 by a manual NiTiinstrument No. 20 (1^(st) category, 1^(st) class) having an approximate4% taper and a non-cutting tip (e.g., 1633 B) the endodontist, may beable to directly reach the apex 1650 by using electrically operatednon-cutting tip NiTi instruments, starting by enlarging the path 1655with a file No. 20 having an approximate 4% taper (1^(st) category,1^(st) class) then using in increasing order, non-cutting tipinstruments selected from the 1^(st) category, 1^(st) class, from No. 10to No. 20 having an approximate 2% taper and then No. 20 with anapproximate 4% taper (1^(st) category, 1^(st) class), and finally usinginstruments Nos. 20 to 25 having an approximate 2% taper of the 2^(nd)category followed by instruments No. 20 or 25 having a 4% taper of the3^(rd) category.

It is worth noting that the root canal is irrigated with sodiumhypochloride and EDTA (Ethylenediaminetetraacetic acid) at each relevantstep of process 2100.

The following X-Rays (FIGS. 25 and 37) provide supporting illustrationsof this novel process 2100:

FIG. 25A shows a hypercalcification, a shoulder, and a broken file inthe mesial canals of tooth no. 36. FIG. 25B shows the broken file. FIG.25C shows the bypassing of the broken file, the penetration of theshoulder and the piercing of the hypercalcification in the 2^(nd) mesialcanal and reaching the apex with the new instrument, according to thepresent invention. FIG. 25D shows the fully hermetic obturation of thetreated root canal.

FIG. 37A shows a blockage in the mesial canal of tooth no. 16 due to ashoulder. FIG. 37B shows the elimination of the shoulder with the newinstrument reaching the apex, according to the present invention.

VI—Method of Penetrating Root Obstructions Resulting from a PreviousRoot Canal Treatment

With reference to FIG. 17, it comprises FIGS. 17A and 17B andillustrates an exemplary tooth 1700 having a root canal 1712 that isblocked or obstructed by, for example a residual, hardened paste 1710from a previous root canal treatment. With further reference to FIGS.22A and 22B, the treatment method 2200 is performed according to thefollowing steps:

As further illustrated in FIG. 17A, the endodontist opens the root canal1712 at step 2210 of FIG. 22A using instruments 1720 selected from the1^(st) category, 2^(nd) class, starting with file No. 10 with anapproximate taper 2%, in order to create an initial path 1733 in theexisting residual paste 1710, using an instrument 1725 with a cuttingtip, to a depth of approximately 2 mm to 3 mm, using an appropriatesoftening agent.

At step 2220, the endodontist enlarges the opened initial path 1733 withinstruments 1720 selected from the 2^(nd) and 3^(rd) categories.

At step 2230, the endodontist pierces again the residual paste 1710,through the initial path 1733, using an instrument 1720 selected fromthe 1^(st) category, 2^(nd) class, file No. 15, to an additional depthof approximately 2 mm-3 mm.

At step 2240, the endodontist enlarges the width of the initial path1733 using instruments 1720 selected from the 2^(nd) and 3^(rd)categories.

With further reference to FIG. 17C, and to step 2250 of FIG. 22B, theendodontist pierces again the widened initial path 1733 using aninstrument 1730 selected from the 1^(st) category, 2^(nd) class, fileNo. 15, with a possible recourse to file No. 10 of the 1^(st) category,2^(nd) class, until the apex 1750 is reached.

At step 2260, the endodontist enlarges the opened path 1755 withinstruments selected from the 2^(nd) and 3^(rd) categories inpreparation for the obturation step.

In the event an unexpected obstruction is faced inside the resistantpaste, the aforementioned steps of process 2200 will be used dependingon the nature of the encountered obstruction, i.e. fractured instrument,hypercalcification, curved root canal or shoulder.

It should be clear that if the obstruction within the root canalincludes a resistant, residual paste 1710, the process 2000 describedearlier in connection with FIG. 20 relating to the piercing of thehypercalcification, can be used, in the same sequence from step 2030through step 2070.

As illustrated at step 2270 and also in FIG. 14E, upon completion ofstep 2260 as described earlier, the endodontist clears the widened rootcanal of any debris, as is known in the field, in preparation for thefinal obturation step.

As illustrated at step 2280 and also in FIG. 14F, the endodontistobturates the root canal with the appropriate filling material 1446, asis known in the field.

It is worth noting that the root canal is irrigated with sodiumhypochloride and EDTA (Ethylenediaminetetraacetic acid) at each relevantstep of process 1900.

The following X-Rays (FIGS. 27, 33, 37, 38) provide supportingillustrations of this novel process 2200:

FIG. 27A shows three broken files with resistant paste in tooth no. 35blocking the totality of the root canal. FIG. 27B shows the bypassing ofthe three broken files and the piercing of the resistant paste with thenew instrument reaching the apex, according to the present invention.FIG. 27C shows the fully hermetic obturation of the root canal.

FIG. 33A shows an incomplete root treatment of tooth no. 35 due tohypercalcification blocking the third apical of the root canal. FIGS.33B, 33C, and 33D show the piercing of the old resistant paste andprogressively piercing the hypercalcification with the new instrumentreaching the apex, according to the present invention.

FIG. 37A shows a blockage in the mesial canal of tooth no. 16 due to ashoulder and a resistant paste. FIG. 37B shows the elimination of theshoulder and the piercing of the resistant paste with the new instrumentreaching the apex, according to the present invention.

FIG. 38A shows a false canal and a resistant paste in tooth no. 37. FIG.38B shows the avoidance of the false canal and the piercing of theresistant paste with the new instrument reaching the apex, according tothe present invention.

It is to be understood that the specific embodiments of the inventionthat have been described are merely illustrative of certain applicationof the principle of the present invention. Numerous modifications may bemade to the present instruments and methods described herein withoutdeparting from the spirit and scope of the present invention.

What is claimed is:
 1. A file for root canal treatment having a shankwith a generally circular cross sectional area.
 2. The file according toclaim 1, wherein the shank terminates in a tip.
 3. The file according toclaim 2, wherein the tip is a generally conical cutting tip.
 4. The fileaccording to claim 2, wherein the tip is a generally conical non-cuttingtip.
 5. The file according to claim 2, wherein the shank includes aroughened lateral surface.
 6. The file according to claim 5, wherein thelateral surface contains a plurality of striated grooves.
 7. The fileaccording to claim 6, wherein the striated grooves include any one ormore of: horizontal, vertical, and transversal grooves.
 8. The fileaccording to claim 7, wherein the striated grooves are separated bysmooth areas.
 9. The file according to claim 5, wherein lateral surfacecontains a plurality of saw teeth.
 10. The file according to claim 5,wherein the lateral surface is sandblasted.
 11. The file according toclaim 2, wherein the tip is beveled.
 12. The file according to claim 2,wherein the file is any one of: a hand operated instrument and anelectrically rotating instrument; wherein the shank is made from any oneof: stainless steel with nos. ranging from 10 to 25; NiTi with nos.ranging from 20 to 25 for the hand operated instrument; and NiTi withnos. ranging from 10 to 25 for the electrically rotating instrument; andwherein the shank has a taper that ranges between 0% and 4%, and alength that ranges from approximately 12 mm to 32 mm.
 13. The fileaccording to claim 2, wherein the file is a hand operated instrument;wherein the shank is made from any one of: stainless steel with nos.ranging from 6 to 20, and NiTi with nos. ranging from nos. 20 to 40; andwherein the shank has a taper that ranges between 0% and 4%, and alength that ranges from approximately 12 mm to 32 mm.
 14. The fileaccording to claim 2, wherein the file is an electrically rotatinginstrument; wherein the shank ranges from nos. 10 to 20; and wherein theshank has a taper that is approximately 2%, and a length that rangesfrom approximately 21 mm to 32 mm.
 15. The file according to claim 2,wherein the file is an electrically rotating instrument; wherein theshank ranges from nos. 20 to 40; and wherein the shank has a taper thatranges between 4% and 10%, and a length that ranges from approximately21 mm to 32 mm.
 16. A file for root canal treatment having a shank thatincludes a spiral section with an upper cylindro-conical section. 17.The file according to claim 16, wherein the shank terminates in a tip;and wherein the tip is any of a cutting tip or a non-cutting tip. 18.The file according to claim 16, wherein the cylindro-conical sectionincludes a lateral surface; and wherein the lateral surface of thecylindro-conical section contains striated grooves.
 19. The fileaccording to claim 18, wherein the striated grooves include any one ormore of: horizontal, vertical, and transversal grooves.
 20. The fileaccording to claim 18, wherein the striated grooves are separated bysmooth areas.
 21. The file according to claim 16, wherein the spiral andcylindro-conical sections are sandblasted.
 22. The file according toclaim 16, wherein the shank ranges from nos. 10 to 40; and wherein theshank has a taper that ranges between 2% and 10%, and a length thatranges from approximately 12 mm to 32 mm.
 23. A file for root canaltreatment comprising: a shank; and wherein the shank includes a seriesof cylindro-conical sections that are inter-spaced with a series ofspiral sections.
 24. The file according to claim 23, wherein the tip isa cutting tip.
 25. The file according to claim 23, wherein the tip is anon-cutting tip.
 26. The file according to claim 23, wherein eachcylindro-conical section includes a lateral surface; wherein the lateralsurface of the cylindro-conical section contains striated grooves; andwherein the striated grooves are formed of any one or more of:horizontal, vertical, and transversal grooves that are separated bysmooth areas.
 27. The file according to claim 23, wherein the spiral andcylindro-conical sections are sandblasted.
 28. The file according toclaim 23, wherein the shaft ranges from nos. 10 to 40; and wherein theshaft has a taper that ranges between 2% and 10%, and a length thatranges from approximately 12 mm to 32 mm.
 29. A root canal method forbypassing or penetrating root obstructions in a root canal, comprising:using a file having a shank with a generally circular cross-sectionalarea; wherein the obstructions result from any one or more of: afractured instrument, root obstacles, shoulders, resistant paste,hypercalcification, and curvature within the root canal.